There is increased interest in understanding how stress reduces coral resistance to disturbances and how acclimatization increases the ability of corals to resist future stress. Most extreme low tides at Gorgona Island, which expose reef flats to air, do not appear to negatively affect corals because corals usually do not undergo lethal bleaching during such events. However, coral physiology and fitness may be impacted by this phenomenon. The aim of this study was to evaluate whether corals exposed to air have modified biological functions to resist bleaching. To test this, an extreme low-tide event was simulated in the field. Colonies of Pocillopora damicornis were exposed to air for 15 or 40 min over the course of one, two, or three consecutive days. This procedure was repeated for one to three months. Colonies of P. damicornis exposed to air had reduced fecundity, decreased zooxanthellae density, and changed color from darker to lighter. However, the growth rate of exposed corals was similar to that of non-exposed colonies. We conclude that short periods of subaerial exposure during extreme low tides are not lethal to P. damicornis, but negatively affect sexual reproduction, which might have deleterious effects at the population level. The periodic occurrence of extreme low tides in the tropical eastern Pacific may be one factor responsible for the high rate of asexual reproduction (e.g., fragmentation) in pocilloporid corals of this region.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This study was co-funded by a Jovenes Investigadores scholarship from the Colombian Department of Science, Technology and Innovation awarded to ALC and Grant No. 7935 from the Universidad del Valle awarded to FAZ. Special thanks to Emily Giles (Universidad Austral de Chile, Valdivia) for reviewing the English version of the manuscript and for her thoughtful suggestions. Thanks to editor in chief Howard Lasker, the topic editor and two anonymous reviewers for constructive criticism and comments that improved the paper. We thank members of the Coral Reef Ecology Research Group at Universidad del Valle for their help during the fieldwork, the Administrative Unit of National Natural Parks of Colombia for providing research permits, and the staff of the Henry von Prahl Scientific Station at Gorgona Island for logistic support.